Posted by Alan Bowes on November 04, 1997 at 17:25:11:
In Reply to: Locking Diff. for M-37? posted by Tom Willcox on November 03, 1997 at 22:25:24:
I believe that a Lock-Rite model 1210 will work. It can be had for somewhere around 260 to 270 US dollars, plus installation (or do it yourself).
Caution: The rear axle shafts on an M37 are not the most durable around. If you put a locking differential in (or even a limited-slip unit), it will increase the stress on the shafts. If you are serious about this, I'd recommend having a set of custom shafts made up. This is not terribly expensive IF the shop can find some blanks that can be modified. If they have to make up shafts from scratch out of steel billets, then heat treat them, the price will be significantly higher. I've had custom shafts made from blanks for about 275 dollars per pair, though I haven't researched shafts for an M37. I just replaced a shaft in my M37 with an NOS shaft because the old shaft had a noticeable twist in it, and it's a stock open differential. I know a couple of other blokes who have also had to replace rear shafts on their M37s. It seems the long left-rear shaft is more susceptible to twisting and breakage, perhaps due to a different forging technique as well as its length.
I may consider a Lock-Rite myself if I can find some reasonably priced higher-strength axle shafts. That said, you will probably find people who have had no problem with lockers in their M37s, but sometimes it's a combination of careful driving, having a good stock shaft(s), and maybe a little luck. You could also stay with the stock shafts and keep an extra or two on hand when you go off-roading...just in case.
Regards,
Alan
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